Long rod type suspension insulators with spiral flange and at least one pin-type terminal



7 Nov. 12, 1963 Q J. Mous ou 3,110,759

' E SUSPENSI 5 LONG ROD TYP ON INSULAT WITH SPIRAL FLANGE AND AT LEAST ONE PIN-T TERMINAL FiledJuly 1.8, 1960 2 Sheets-Sheet 1 I INVENTOR. (JEAN Moussou fi? Q/ A FZNEYS LATORS PIN-TYPE WITH SPI TERMIN NOV. 12, 1963 J ousso LONG ROD TYPE SUSPENSION INSU FLANGE AND AT LEAST ONE Filed July 18, 1960 ecs-Sheet 2 dEA/v Moussou MW I II m fifid l P M @m United States Patent 3,110,759 LONG ROI) TYPE SUSPENSION INSULATORS WITH SPIRAL FLANGE AND AT LEAST ONE PIN-TYPE TERMINAL Jean Moussou, Pouzac, France, assignor to Compagnie Generale dElectro-Ceramique, Paris, France, a company of France Filed July 18, 1960, Ser. No. 43,643 Claims priority, application France July 29, 1959 3 Claims. (Cl. 174-182) The present invention relates to solid-shank suspension insulators for electric power lines, of the types generally known as long bar insulators.

These insulators generally consist of an insulating shank provided with ribs and two metal fittings sealed to the exterior of two bosses at the ends of the insulating shank.

According to the invention it is proposed to reduce the length and the weight of insulators while retaining their insulating capacity and improving their resistance to arcing. For this purpose at least one of the fittings is sealed in the interior of a cavity or recess provided at one end of the shank.

The following description with reference to the accompanying drawings, given by way of example only, will make it clear how the invention is to be carried into eilect, the details appearing in the description and the drawings being, as will be understood, part of the said invention.

FIGURE 1 of the accompanying drawings shows an example of a prior art long bar insulator.

FIGURE 2. shows an insulator corresponding to that of FIG. '1 but modified in accordance with the invention.

FIGURE 3 is a longitudinal section of a long bar in sulator in accordance with the invention.

FIGURES 4 and 5 are details of FIGURE 3 on a larger scale.

FIGURE 6 is a longitudinal section of part of a further embodiment of the invention.

FIGURE 7 is an elevational partially sectional view of a further embodiment of this invention.

FIGURE 8 is an elevational partially sectional view of a still further embodiment of this invention.

In the known form of the long-rod or long-bar type insulator (FIG. 1), the insulator is constituted by a shank or body portion 1 provided with ribs 2. The shank 1 is provided at its two ends with two bosses 3 and 4 to which are sealed respectively two caps 5 and 6 by means of suitable cement 7. Caps 5 and 6 are also provided respectively with pins 8 and 9. The long-rod or longbar type insulator is well known in Europe and has been standardized in the German Standard for Langstabisolatoren L, DIN 48012, revised November 1955 to Vollkernisolatoren VKL, DIN 48006. This type of insulator is illustrated on page 308, FIGURE 441, of the AEG Manual-Generation-Transmission-Electrical Installations published by Allgemeine Elektricitats-Gesellschaft, Verlag W. Girardet-Essen, Germany.

The insulator in accordance with the instant invention as shown in FIGURE 2, comprises a body portion 10 having ribs 11 and boss :12 at one end thereof. Cap 13, provided with pin 14, is externally sealed on boss 12 by means of cement 15. End 16 of body portion 10 is provided with cavity 17, in which is sealed pin 18 having flange 19 by means of suitable cement 20. The section of the pin 18 depends upon the tractive force it must withstand and determines the diameter of the cavity. The length of the pin and the depth of the cavity are determined by the sealing area which is required, having regard to the shearing force allowable in the sealing area at the walls of the cavity, which are for this purpose rendered rough by the deposition of a layer 21 of fired ceramic Patented Nov. 12, 1963 particles stuck to the enamel. This roughened layer 21 could alternatively be replaced by grooves provided on the walls of the cavity. v

The insulator of FIG. 2 shows a strengthening of the shank 10 at the end having the cavity 17. When the diameter of the shank is such that despite the presence of the cavity the annular section of the end is large enough to withstand the tractive force, this strengthening is not necessary.

A chain of elements .of the form shown in FIG. 2 is shorter and lighter than the chain formed by the corresponding kno wn elements of FIG. 1.

The insulating shank with a boss for scaling to an external cap can be fired while supported by a prolongation of the boss which is truncated after firing.

According to the circumstances of use and the requirements of firing, the boss for external sealing can be at the upper or lower end of the insulator. It is also possible, especially in the case of long bar insulators, to place links constituted by pins sealed internally at both ends of the insulator (FIGS. 3, 4, 5 and 7).

FIG. 3 shows an insulator with superposed ribs of which the leakage path is at least equal to that of the form shown in FIG. 1 but whose dimensions are less. In the embodiment of FIG. 3 the insulating body constituted by the shank 22 and the ribs 23 is provided at its reinforced ends 24 and 25 respectively with cavities 26 and 27 in which pins 28 and 29 are sealed in known manner by means of a cement 30.

FIGURES 4 and 5 show on an enlarged scale the details of the sealing of the pins 28 and 29 in the cavities 26 and 27 at each end 24 and 25. In order to ensure the adherence of the cement to the walls of cavities 26 and 27, these are provided with a rough adherent layer 31 of fired ceramic particles stuck to the glaze. This rough layer could otherwise be replaced by grooves provided on the walls of the cavity. The fixing links or pins 28 and 29 comprise respectively fixing ring portions 32 and 33 and securing pin portions 34 and 35 Whose greatest section is determined by the mechanical tractive force which the insulator must withstand. To increase the flexibility of the sealed part of the link, the cross-sections of the re spective pin portions 34 and 35 of pins 28 and 29 decrease regularly towards their respective ends. =Pin portions 34 and 35 are provided with thin ribs 36 to ensure the adherence of the pins to the cement. To give greater elas ticity to the assembly, an elastic or plastic layer 37 is dc posited on the bottom of the ribs and the surface of the pin in such a way that the cement cannot penetrate to the bottom of the space between the ribs. These con structional details assist in spreading the shearing forces uniformly along the cavity instead of concentrating them in the area of the bottom of the seal.

The strengthening of the ends 24 and 25 only slightly changes the outline of the insulator, for it is easy to arrange the dimensions of the cavity to be such that the critical region of the bottom of the cavity is contained in the bulge of a rib. Since the stress in the ceramic decreases from the bottom of the cavity towards the edge, the section of the ceramic body between the two end ribs 3 8 and 39 (FIG. 4), or 41 and 40 (FIG. 5), can decrease from 38 towards 39 or from 41 towards 40, which helps to limit the change in the normal profile.

It has been established that an insulator in accordance with the invention of the type L 14 in accordance with German Standard DIN 48012 can, other things being equal, be reduced by in length and nevertheless carry an additional rib on the shank, that is to say ofier in all a longer leakage path.

The modification of the ends for strengthening does not involve any additional diificulty since the insulator can c9 be turned in the same extruded blank by means of a slightly modified template.

The insulating bar constituted by the shank and the ribs should be fired either standing or hanging according to the circumstances. When the insulator is fired standing it can rest during the firing on a support bearing on the unglazed surface of the cavity. When the insulator is fired suspended it is supported by a prolongation broken off after firing which is represented by broken lines in FIG. 3. The broken surface being un-glazed, the fixing link 28 comprises a flange 42 protecting this surface which could also be coated with an insulating epoxy resin such as that sold under the trademark Arald-ite.

The links of the insulator can of course be provided with the usual protection arrangements: spikes or rings.

FIGURE 6 shows a-sectional view of the end of a long bar insulator with a helical rib. In this embodiment, the insulator comprises an insulating shank 43 around which runs a helical rib 44. In the region of the cavity, the shank 43 is enlarged by modification of the profile of the rib as shown at 45. In the example shown the rib stands out straight from the shank and has a symmetrical profile. It is formed by milling. One passes from the rib of profile 44 to the rib of profile 45 simply by extending the milling cutter radially of the axis of the insulator. The details of sealing in this embodiment are identical to those of FIG. 6.

The embodiment of the invention shown in FIGURE 7 comprises an elongated cylindrical body portion 46. Body portion 46 has superposed thereon spiral or helical flange 4'7. Pins 48 and .9 are respectively sealed in cavities b and 51 provided in body portion 46 by means of appropriate cement 52. The walls of cavities 5t) and 51 are lined with a rough adherent layer 53 of fired ceramic particles stuck by glaze. Pins 48 and 49 are provided with ribs 54 and respectively with fixing rings 55 and 56.

A chain of elements of the forms shown in FIGURES 2, 3, 4, 5 and 7 is shorter and lighter than the chain formed by the corresponding known elements of FIG- URE 1.

The embodiment of the insulator of this invention shown in FIGURE 8 comprises an elongated cylindrical body portion 57 having superposed thereon a spiral or helical flange 58. End 59 of body portion 57 is provided with a cavity 60' having pin 61 internally sealed therein by means of suitable cement 62. Pin 61 is provided with fixing ring 63 and ribs 6 4. The walls of cavity 60- are provided with roughened layer 65 of fired ceramic particles stuck by glaze. End '66 is provided with boss 67. Cap 68 having pin 69 is externally sealed on end 66 by means of suitable cement 70.

In the embodiments of FIGS. 2, 3, 4, 5, 6, 7, and 8 the external diameter of the ribs has been deliberately maintained despite variations in the diameter of the shank in order to be able to use the same extruded blank as that required for making thecorre-sponding known insulator. It is clear that one could, without departing from the scope of the invention, give a larger diameter to the end ribs. It will of course be necessary to start with an extruded blank of appropriate diameter. A helical rib or ribs may be given a pitch and inclination on the strengthened parts at the ends of the shank difierent from those on the central part. To do this it is only necessary to move the milling cutter at the appropriate speed during the manufacture.

In the case of insulators with helical ribs, it is preferable in order to achieve symmetry of the stresses in the critical sealing region to provide the shank with several regularly spaced helical ribs. 7

It is clear that strengthening of the shank is only necessary if the diameter of the shank is insuflicient to allow the provision of a sealing cavity. When the cavity can be provided while leaving an annular section of the ceramic in the region at the bottom of the seal sufficient to resist the tractive forces, it would clearly be useless to alter the external pro-file of the insulating bar. be the case for an insulator with helical ribs.

In effect, the conception of this insulator is such as to allow a small pitch since in rain the ribs cannot be shortcircuited by threads of water. The number of turns of the helix being increased, the depth of the turns can be reduced while retaining a suitable leakage path. Thus the insulator, for an external diameter comparable with that of a similar insulator with superposed ribs, can have a considerably stronger shank. It will be understood that in this case it will not be necessary to strengthen the ends to provide the seals, which simplifies the construc tion.

It has been shown that suspension insulators of the long bar type with internal seals not only offer the advantage of a reduction in length for the same insulation, whence results economy in the whole of the installation of the line, but also a particularly good resistance to the power arc, especially in the case of insulators with helical ribs. This behaviour of insulators with internal seals reduces the risks of breakdown of the lines. These insulators also have small radiophonic disturbance voltages.

Support insulators with helical ribs have been proposed with internal fittings but this method of securing the fittings has not been applied to line suspension insulators such as those described in the Germany Standard DIN 480 12. It is in this latter application that the method is most valuable, as has been shown above.

What I claim is:

l. A solid core high tension suspension insulator comprising an elongated long-rod type insulator body, said body having at least one external spiral flange disposed extending from one end to the other thereof, at least one end of said body having a blind cavity extending axially inwardly from the face of said one end and into said body, and said body having a first pin-like suspension fitting, a substantial portion of which is internally sealed within said cavity at said one end, and a second suspension fitting sealed at the other end of said body.

2. A solid core high tension suspension insulator comprising an elongated long-rod type insulator body, said body having at least one external spiral flange disposed extending from one end to the other thereof, one end of said body having a blind cavity extending axially inwardly from the face of said one end and into said body, and said body having a first pin-like suspension fitting, a substantial portion of which is internally sealed within said cavity at said one end, and a second cap-like suspension fitting externally sealed at the other end of said body.

3. A solid core high tension suspension insulator comprising an elongated long-rod type insulator body, said body having at least one external spiral flange disposed extending from one end to the other thereof, each end of said body respectively having a blind cavity extending axially inwardly from the respective face of each of the respective ends and into said body, and said body having a first pin-like suspension fitting, a substantial portion of which is internally sealed within the cavity at one end of said body, and a second pin-like suspension fitting, a substantial portion of which is internally sealed within the cavity at the other end of said body.

References Cited in the file of this patent UNITED STATES PATENTS 1,257,516 Muckey Feb. 26, 1918 1,894,292 Oramer Feb. '17, 1933 1,958,435 Hawley May 15, 1934 2,043,523 Van Atta June 9, 1936 2,155,848 Taylor Apr. 25, 1939 FOREIGN PATENTS 384,526 France Feb. 6, 1908 428,569 Great Britain May 15, 1935 456,500 Italy Feb. 2, 1938 747,131 Great Britain Mar. 28, 1956 1,168,668 France Sept. 1, 1958 This will usually 

1. A SOLID CORE HIGH TENSION SUSPENSION INSULATOR COMPRISING AN ELONGATGED LONG-ROD TYPE INSULATOR BODY, SAID BODY HAVING AT LEAST ONE EXTERNAL SPIRAL FLANGE DISPOSED EXTENDING FROM ONE END TO THE OTHER THEREOF, AT LEAST ONE END OF SAID BODY HAVING A BLIND CAVITY EXTENDING AXIALLY INWARDLY FROM THE FACE OF SAID ONE END AND INTO SAID BODY, AND SAID BODY HAVING A FIRST PIN-LIKE SUSPENSION FITTING, A SUBSTANTIAL PORTION OF WHICH IS INTERNALLY SEALED WITHIN SAID CAVITY AT SAID ONE END, AND A SECOND SUSPENSION FITTING SEALED AT THE OTHER END OF SAID BODY. 